Method for low temperature chemical vapor deposition of low-k films using selected cyclosiloxane and ozone gases for semiconductor applications

Abstract

A method is described for forming a low-k dielectric film, in particular, a pre-metal dielectric (PMD) on a semiconductor wafer which has good gap-filling characteristics. The method uses a thermal sub-atmospheric CVD process that includes a carbon-containing organometallic precusor such as TMCTS or OMCTS, an ozone-containing gas, and a source of dopants for gettering alkali elements and for lowering the reflow temperature of the dielectric while attaining the desired low-k and gap-filling properties of the dielectric film. Phosphorous is a preferred dopant for gettering alkali elements such as sodium. Additional dopants for lowering the reflow temperature include, but are not limited to boron, germanium, arsenic, fluorine or combinations thereof.

We claim:  
     
       1. A pre-metal dielectric (PMD) semiconductor structure comprising: 
       a semiconductor wafer having features on a surface of said wafer, wherein said features are spaced to form at least one gap between said features, wherein said at least one gap has an aspect ratio greater than about 3; and  
       a low-k film covering said surface, wherein said low-k film fills said at least one gap without having a void, and said low-k film includes a dopant.  
     
     
       2. The PMD structure of  claim 1  wherein said low-k film has a dielectric constant less than about 3. 
     
     
       3. The PMD structure of  claim 1  wherein said dopant comprises phosphorous. 
     
     
       4. The PMD structure of  claim 3  wherein said dopant further comprises a second dopant selected from the group consisting of boron, germanium, arsenic, fluorine and a combination thereof. 
     
     
       5. The PMD structure of  claim 1  wherein said features comprise gate conductor stacks. 
     
     
       6. The PMD structure of  claim 1  wherein said low-k film has a reflow temperature less than about 725° C. 
     
     
       7. A pre-metal dielectric (PMD) semiconductor structure comprising: 
       a semiconductor wafer having gate conductor stacks on a surface of said wafer, said gate conductor stacks spaced to form at least one gap having an aspect ratio greater than about 3; and  
       a low-k film covering said surface, said low-k film having a dielectric constant less than about 3, wherein said low-k film fills said at least one gap without having a void and wherein said low-k film includes phosphorous sand a dopant selected from the group consisting of boron, germanium, arsenic, fluorine and a combination thereof.  
     
     
       8. A low-k film comprising: 
       a carbon-containing dielectric material;  
       phosphorous; and  
       a dopant selected from the group consisting of boron, germanium, arsenic, fluorine and a combination thereof, wherein said low-k film has a dielectric constant less than about 3 and having a reflow temperature less than about 725° C.  
     
     
       9. The PMD structure of  claim 7  wherein said low-k film has a reflow temperature of less than about 725° C.